1. Field of the Invention
The present disclosure relates to an image forming apparatus, such as a laser printer, a copying machine, or a fax machine, employing the electrophotographic recording method.
2. Description of the Related Art
Conventionally, there are known image forming apparatuses, such as copying machines and laser printers, employing the electrophotographic recording method. An image forming apparatus employing the electrophotographic recording method performs the following electrophotographic processes as discussed in Japanese Patent Application Laid-Open No. 2001-281944. First, a surface of a photosensitive drum is evenly charged to, for example, −600V by a charging device. Then, a laser exposure apparatus emits a laser beam onto the photosensitive drum, and an electrostatic latent image is formed on the photosensitive drum. Further, toner is attached to the electrostatic latent image by a development apparatus. The toner image is transferred onto a recording medium by a transfer apparatus.
The toner that remains on the photosensitive drum is removed by a drum cleaning unit. Further, the remaining electric potential of the photosensitive drum is neutralized by illumination of a pre-exposure lamp. Then, the photosensitive drum is ready for the next image forming.
In forming an electrostatic latent image on the photosensitive drum surface of the image forming apparatus employing the above-described electrophotographic method, it is important to control the charge potential of the surface of the photosensitive drum in advance. Various control methods are proposed for this control of the charge potential including the above-described pre-exposure lamp. However, a simplified configuration is desired from the viewpoint of cost reduction and downsizing of the apparatus main body.
On the other hand, in recent years, color printers have been widely used and have become to be the main stream of the printers. These color printers are capable of changing processing speeds so as to deal with printing of various types of media including rough paper and glossy paper as well as plain paper. In addition, color printers are not only used for producing color prints, but also produces monochromatic prints as well. When a color printer performs monochromatic printing, it also changes the processing speed. Since the printer needs to correspond to various processing speeds, operation and control of the printer tend to be complicated.